Cognitive dissonance occurs when the brain recognizes it’s holding two conflicting beliefs. For example, let’s say you have always detested olives, and then one day your spouse sneaks them into a pasta sauce and you find them delightful. Or let’s say you’ve always considered yourself a conservative, but an election rolls around and you’re drawn to a liberal candidate. Your brain experiences dissonance that it will want to dispel.

Festinger says that if you spend a ton of effort on a task you value, your brain considers that a worthwhile use of resources. But what if you spend a high effort on something you don’t consider valuable? Your brain hates cognitive dissonance so it justifies the effort, usually by deciding the task actually was valuable. Thus cognitive dissonance can trick your brain into perceiving you value a particularly difficult or unenjoyable task, which in turn can spur motivation and engagement.